1. Field of the Invention
The present invention relates to a sheet discharge device for discharging sheets onto a sheet receiving tray inclined relative to the vertical direction.
2. Description of the Related Art
A sheet discharge device configured to sequentially discharge and stack sheets onto a sheet receiving tray by using sheet discharge rollers is usually employed in inkjet printing machines, stencil printing machines, laser beam printers, thermal transfer printing machines, copying machines (copiers), and the like.
As a relevant sheet discharge device, Japanese Unexamined Patent Application Publication No. 2002-12362 proposes a sheet stacking device, a post-processing device, and an image forming device which can prevent misalignment of sheets during an operation to shift a sheet receiving tray.
Now, the relevant sheet stacking device will be briefly described by referring to Japanese Unexamined Patent Application Publication No. 2002-12362.
In a relevant sheet stacking device 100 shown in FIG. 1, a side panel 101 of the sheet stacking device 100 is provided extending in the vertical direction.
A sheet receiving tray 102 to stack discharged sheets P is provided on an outer side of the side panel 101 in an inclined state at a predetermined angle relative to the side panel 101. This sheet receiving tray 102 is provided movable upward and downward along the side panel 101 and shiftable in the sheet width direction perpendicular to the sheet discharge direction of the sheet P (direction normal to FIG. 1) for the purpose of sorting sheets P.
Sheet discharge rollers 103 including pairs of drive roller 103A and driven roller 103B for discharging a sheet P are provided rotatably in an upper side of the side panel 101.
A sheet reverse roller 104 is provided above a top surface 102a of the sheet receiving tray 102 in the vicinity of a base end 102b of the sheet receiving tray 102. This sheet reverse roller 104 is rotatable by the same drive source as each drive roller 103A of the sheet discharge rollers 103.
When a discharged sheet P falls down by its own weight along the sheet receiving tray 102 inclined at a predetermined angle or on a sheet(s) P stacked thereon, the sheet reverse roller 104 moves the discharged sheet P from the trailing end in the opposite direction to the sheet discharge direction and hits the trailing end against the side panel 101. As a result, the trailing ends of multiple sheets P stacked on the sheet receiving tray 102 are aligned along the side panel 101.
When the sheet receiving tray 102 is shifted, the shifting operation is performed after lowering the sheet receiving tray 102 by a lowering distance k to separate the top surface of the sheet(s) P stacked on the sheet receiving tray 102 from the sheet reverse roller 104.